Removing oxide from Stibarsen and Arsenic

Hi All,

I've been collecting stibarsen and arsenic from old (90 year old) waste rock dumps at the Engineer Mine in northern British Columbia recently and find that most of it is coated with oxides. Generally, the arsenic seems to have a red-purple oxide coating and the stibarsen a yellowish-white coating. Any suggestions of improving these specimens? I have some ideas but am really after someone to relate solid experience with this sort of "cleaning".

David K. Joyce

Try some iron out and see if it works.

Rock Currier
Crystals not pistols.

I assume that these coatings are arsenic oxides? (Perhaps the red-purple one is mixed with a bit of metastibnite?) If so, they are very easily soluble in KOH or NaOH solutions (dilute caustic soda). Don't leave it in long; just a few seconds should be enough. You might need to follow up with a dilute lacquer to prevent reoxidation.

Dave,

Could it be carmine red rather than red-purple? I'm back on my we need a color reference chart soap box.

Perhaps it's an iridescent thin film of kermesite on the stibarsen. The arsenic will stay dull no matter what you do.

A flash in HF removes thin films of antimony oxides. The monster stibnites from the Lucky Knock Mine in Okanogan County, Washington had very thick films of yellowish antimony oxides and were all treated with HF by Carl Ferr of Spokane's "Ore Incorporated" mineral shop, The result was shiny but pitted stibnite. The specimens were all mined by the late Elwin Magill. The Lucky Knock is still in the Magill family. It is surrounded by ranches, and the ranchers do not allow any access.

Ammonium bi-fluoride might work for a thin film of antimony oxides.

Bart

Hi Guys,

Thanks for the suggestions! I think I'll try Rock's suggestion first since it is easiest and, if it doesn't work, move on to the more toxic chemicals (except the HF! -don't have facilities). BTW, Bart, as I mentioned, the reddish stuff seems to be on the arsenic, not the stibarsen.

Further suggestions are welcome. I'll let you know what works.

Cheers,
David K. Joyce